1. Field of the Invention
The present invention is generally concerned with measuring a distance related to the interpupillary distance of a person, either the interpupillary distance directly, or half the corresponding interpupillary distance.
2. Description of the Prior Art
At present this measurement is performed manually, using an interpupillary distance measuring device.
An interpupillary distance measuring device of this kind is described in French patent No. 1 506 352, for example.
It comprises a light source adapted to produce a corneal reflection on at least one of the two eyes of the person concerned, in practice on each of the latter, and a measurement reference mark relative to which the corneal reflection can be located.
In practice two movable markers are provided for this purpose, which are made to coincide with the respective corneal reflections and the distance between which is then measured with the aid of the associated measurement reference mark.
Although this arrangement, somewhat rudimentary and therefore inexpensive, has given and can give further satisfaction, it has the particular disadvantage of requiring reticules to be moved, so that it is a relatively slow process, and the results are conditioned by the skill of the operator.
A general object of the present invention is to provide an arrangement whereby a distance related to the interpupillary distance of a person can be measured in a simple, automatic and therefore rapid way.